Our view of the stars could change forever

The night sky is now invaded by satellites and space junk, posing a significant threat to observations of the cosmos.

Pollution is one of the most serious and concrete problems on Earth, with junk representing an ever-increasing criticality. Garbage that over the centuries has invaded the land and sea, and now is beginning to "colonize" space, or at least the known. It's no coincidence then that the night sky is filling up with shiny satellites and space junk, which are increasingly taking on the profile of a real threat to the cosmos, as well as to astronomical research.

Researchers have in fact discovered that the more than 9.300 tons of disused space objects orbiting Earth - including inoperative satellites and fragments of spent rocket stages - increase the overall brightness of the night sky by about 10 percent over large parts of our planet. Of course, an increase of this magnitude is making it increasingly difficult for astronomers to make accurate measurements of the universe, increasing the likelihood of missing some discoveries significant to scientific progress. Similarly, the values laid out in the report published in the journal Monthly Notice of the Royal Astronomical communicate that vast areas of our planet are considered polluted by light.

In their study, scientists calculated the change in brightness by developing a well-defined and fairly accurate model that takes into account the average size and brightness of each piece of debris. Satellites and junk floating in space play havoc with astronomical images, scattering reflected sunlight and producing bright streaks that make objects of astrophysical interest indistinguishable, since they are brighter than stars and planets. Overall, then, while we can hear eerie messages from Venus, observing the sky is becoming an increasingly complex task for astronomers. A warning, this one, that comes from the viva voce of study co-author John Barentine, director of public policy for the International Dark-Sky Association:

Unlike light pollution from the ground, this kind of artificial light in the night sky can be seen over much of the Earth's surface.

Astronomers build observatories away from city lights to look for dark skies, but this form of light pollution has a much wider geographic reach.

The effect, again according to the study, becomes more pronounced when observing the sky with low-resolution detectors, such as the human eye. And that's why stargazing as we do today may in the future be a not-so-trivial practice, marred by anomalous diffuse brightness.

For Barentine and his team, we're just at the beginning: in the years to come, the sky will become even brighter due to "mega constellations" of commercial satellites that aim to provide global Internet access even in the most remote areas of the Earth. As of today, there are at least 12 operators - including giants Amazon, SpaceX and OneWeb - who plan to expand existing networks by launching constellations of thousands of satellites among the stars.

Andrea Guerriero